DCA Diamond Authentication & Certification 2 — Questions and Answers
Question 1: Which grading laboratory is widely considered the most stringent and consistent in diamond certification?
- EGL
- IGI
- GIA (Correct answer)
- AGS
Correct answer: GIA
The Gemological Institute of America (GIA) is the industry standard-setter and is regarded as the most consistent and stringent major grading laboratory.
Question 2: On a GIA diamond grading report, the term 'clarity characteristics' refers to what?
- The diamond's overall polish grade
- Internal and external features used to determine clarity grade (Correct answer)
- The fluorescence intensity rating
- The proportions of the diamond's cut
Correct answer: Internal and external features used to determine clarity grade
Clarity characteristics are the internal (inclusions) and external (blemishes) features plotted on the report's diagram and used to assign the clarity grade.
Question 3: What does the 'girdle' description on a diamond grading report indicate?
- The diamond's table percentage
- The thickness range of the widest perimeter of the stone (Correct answer)
- The depth percentage relative to diameter
- The culet size at the bottom of the diamond
Correct answer: The thickness range of the widest perimeter of the stone
The girdle description on a report indicates the thickness range (from thinnest to thickest) of the diamond's outer edge.
Question 4: A diamond report with a 'Comments' section noting 'Clarity grade is based on clouds not shown' means what?
- The cloud inclusions are too small to plot on the diagram but still affect the clarity grade (Correct answer)
- The diamond has no cloud inclusions
- The clouds are only visible under UV light
- The cloud inclusions were not factored into the clarity grade
Correct answer: The cloud inclusions are too small to plot on the diagram but still affect the clarity grade
This comment indicates clouds are present and affect the grade but are too numerous or small to individually plot on the clarity diagram.
Question 5: Which of the following best describes a 'Type IIa' diamond classification?
- Contains nitrogen impurities giving a yellow tint
- Contains boron making it electrically conductive
- Has no measurable nitrogen or boron, often colorless or near-colorless (Correct answer)
- Contains structural irregularities causing a brown color
Correct answer: Has no measurable nitrogen or boron, often colorless or near-colorless
Type IIa diamonds have no measurable nitrogen impurities, making them chemically pure and often the most colorless diamonds found in nature.
Question 6: When verifying a diamond against its GIA report using the report number, what is the most secure method?
- Checking the number against a printed GIA catalog
- Using the GIA Report Check online database to confirm the report is genuine (Correct answer)
- Calling the retailer who sold the diamond
- Comparing the report number to the diamond's color grade
Correct answer: Using the GIA Report Check online database to confirm the report is genuine
The GIA Report Check online database allows anyone to verify that a GIA report number is genuine and matches the details on the physical report.
Question 7: A diamond described as 'laser inscribed' on its grading report refers to what feature?
- A laser-drilled clarity enhancement that removes dark inclusions
- A microscopic identification number or text inscribed on the girdle (Correct answer)
- A fluorescence pattern caused by UV laser testing
- A laser-cut facet pattern on the crown
Correct answer: A microscopic identification number or text inscribed on the girdle
Laser inscription places a microscopic report number (and sometimes a personal message) on the diamond's girdle, linking the stone permanently to its grading report.
DCA Diamond Authentication & Certification 2
Which grading laboratory is widely considered the most stringent and consistent in diamond certification?